Solenoid pilot controlled main valve for machine tools or the like



7 F. SCHMIDT 2,811,170

SOLENOIDPILOT CONTROLLED MAIN VALVE FOR MACHINE TOOLS OR THE LIKE Filed June 25, 1954- ilnited rates Patent Oi SOLENOID PILOT CONTROLLED MAIN VALVE FOR MACHINE TOOLS OR THE LIKE Franz Schmidt, Schmitten (Taunus), Germany Application June 25, 1954, Serial No. 439,358 Claims priority, application Germany October 29, 1953 6 Claims. (Cl. 137-620) The invention relates to hydraulic control elements for machines and in particular for machine tools.

The control elements of this type hitherto known consist substantially of a cylinder equipped with an electromagnetic control slide valve, the upper surface of which cylinder requires precision working and is provided with suitable apertures which coincide with bores provided with registering passage months in a special common controlgear housing and accommodating this cylinder in a snug fit. According to the number of working cylinders necessary for imparting the tool movement or the like and influenced by the pressure medium, such as water, oil or some other suitable liquid, a number of bores must be provided in the common control gear housing for accommodating the control cylinders coordinated to the individual working cylinders. As a result of the necessary labyrinth of passages, the common control gear housing is difiicult to produce and moreover the inaccessibility makes it difficult to carry out the service which is necessary in order to maintain a constant flow of pressure medium. Furthermore, both the control cylinders and also the bores in the common control gear housing accommodating them are subjected to expensive precision machining in order to ensure a tight snug fit.

To overcome these objections, the problem which the invention sets out to solve is to produce a hydraulic control element which is constructed in a practical manner so that, without any machining beyond the ordinary, it can easily be connected with the corresponding working cylinder so that it guides the fluid medium, carries out accurately the control operations with the required rhythm of the machine and furthermore, while ensuring easy accessibility, enables any desired number of similar control elements to be lined up to form batteries with mutually independent operation but common admission and discharge of the pressure medium.

In solving this problem, the novel feature of the invention consists in that a valve is employed which is accommodated in an oil-tight housing arranged between. the liquid pressure conduit and the passage for the working cylinder in question and which consists of a rotary body, for example a ball; which valve, together with an independent or unsupported piston with which it is preferably in contact, carries out both similar and lagging stroke movements and is axially shiftable with this piston through the pressure fluid loading the outer surface of the piston and valve by means of a known slide valve control, for example, an electromagnetic control gear and rhythmically alternately completely closes the liquid pressure conduit to the working cylinder and the liquid discharge therefrom, but allows the admission and discharge passage of the working cylinder to remain open in any stroke position so that, when the liquid pressure conduit is open and the liquid discharge is correspondingly closed, the liquid feed is eifected and when the liquid pressure conduit is closed and the liquid discharge is open the liquid discharge from the working cylinder takes place.

2,811,170 Patented Oct. 29, 1957 ice To enable the lining up of a plurality of control elements, the liquid pressure conduit and the liquid discharge conduit pass through the housing in transverse direction, the ends of the battery being closable by means of a cover with only one admission and one discharge tube which tubes supply all the control gear housings and the corresponding valves and lead off the liquid therefrom.

Other features are contained in the following description and in the accompanying drawing which illustrates an embodiment of the invention by way of example. In the drawing:

, Fig. '1 is a longitudinal section in the vertical plane through a control element; and

Fig. 2 is a part section through two control elements united to form a battery.

A ball 3 is mounted in a liquid-tight housing 1, between a liquid pressure conduit 2 and a passage 6 of the working cylinder in question within a cage formed preferably by rubber seating rings 4 and a guide 5 so that the ball is capable of limited movement. In its highest stroke position the ball 3 shuts off the pressure medium feed from theliquid pressure conduit 2 and in its lowermost the pressure medium can flow from the passage 6 into the discharge passage 9 and on the other hand, i. e. in lowest position the pressure medium can'flow from the'liquid pressureconduit 2 into the passage 6 leading'to the working cylinder. An independent or unsupported piston 8 is mounted in a cylinder 7 below the ball 3 andthe ball-3 contactsthe tapered upper end. of this piston 8. so that the discharge passage 9 is always free. A pressure medium chamber 11 is connected to the liquid pressure conduit. 2 by means of a passage 15 controlled by an electromagnetic slide valve control gear 12, 13, 18, 18'. Although a single magnet control gear could be used, in thepresent instance a double magnet control gear is preferably provided. At the lower end of the liquid-tight housing 1, the housing 12 of a control slide valve rod 13 is: mounted which covers the pressure medium chamber of the freely movable piston 8 at the bottom and, 'has in addition. to the passage 15 leading into the pressure medium chamber 11, on each side thereof a passage communicating directly or over an interposed'additional pump e. g; a quick-return motion pump with the main pressure stri'cted portion is provided and the conical. end of the, slide valve rod forms the actual etfectivemember of the.

slide valve. The core 18 and the slide valve rod 13 form a unit which has only a single bearing between the core 18 and the eflfective end of the slide valve rod, so

that an easy sliding of the unit is ensured when there is a suitable flow of current through the double magnet 18'. Only a small current intensity is required because at each stroke only one of the magnets is effective. The eiiective end of the slide valve rod 13 allows alternately the inflow from the liquid pressure conduit 2 through the passage 15 into the pressure medium chamber 11 of the piston 8 and the outflow from the pressure medium chamber 11 through the passage 15 to the discharge passage 16.

In Fig. 1 the right hand magnet of the double magnet 18' is active so that the end of the slide valve rod 13 allows the feed from the main passage 2 through the passage 15 into the pressure medium chamber 11 of the piston and closes or shuts off the outflow to the discharge passage 16. Thereby the ball 3 is pressed by the piston 8 against the upper seat ring land as a result the flow from the main passage 2 to the passage 6 for the working cylinder is cut off. The pressure oil in this cylinder now flows underneath the ball 3 through the apertures in theguide 5 and into the discharge passage 9 terminating above the piston 8. By the repeated operation of the left hand magnet of the double magnet 18' the feed from the main passage is shut olf by the end of the slide valve rod 13 and the discharge from the pressure medium chamber 11 to the discharge passage 16 is opened so that the oil pressure of. the liquid pressure conduit 2- acting on the ball 3 presses the ball3 onto the lower seat ring 4 carrying with it the piston 8, with the result that the discharge from the passage 6 is shut off and the flow from the main conduit 2 into the passage6 leading to the working cylinder is freed. With the object of assembling to form batteries, the liquid-tight housing 1 and the slide valve rod housing 12 have continuous or uninterrupted admission and discharge conduits which register when several housings 1 and 12 are coupled together with interposed rubber packings 19 as shown in Fig. 2. Covers 20 provided with connecting'sockets close the two ends of the battery. [Although there are now common admission and discharge points for the pressure oil, the individual control elements can influence the working cylinders to which they are coordinated independently of each other. In the drawing designates the holes for the anchor bolts, 21

a mounting plate and 22 fixing bolts.

It will, of course, be understood that various details of construction may be varied through a Wide range without departing from the principles of this invention and it is, therefore, not the purpose to limitthe patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim:

1. A hydraulic control device for the purpose set forth; I

comprising a liquid-tight housing provided with a liquid pressure conduit and a working cylinder passage and a liquid discharge passage, a cage supported within said housing intermediate said liquid pressure conduit, said working cylinder passage and said discharge passage, said cage comprising upper and lower valve seat rings and an interposed valve guide, a cylinder disposed within said housing beneath said cage, the said liquid pressure conduit and liquid discharge passage having communication with said working cylinder passage through said valve seat rings and said guide, a spherical valve freely disposed within said cage and adapted for alternate seating engagement with one and the other of said seat rings, a piston disposed within said cylinder and being freely movable therein and having an upper portion'engageable with said spherical valve for maintaining said discharge passage open when the valve is seated on the upper seat ring,'a pressure medium chamber in said cylinder beneath said piston, a passage in said housing in communication with said liquid pressure conduit and said pressure medium chamber, a second liquid discharge passage in said housing adjacent said last passage, and a slide valve supported by said housing and being operative to alternately put said pressure medium chamber into communication with said liquid pressure conduit and said last discharge passage.

2. A hydraulic control device according to claim 1, wherein said cylinder is provided in the wall thereof with apertures leading to said first liquid discharge passage, and said upper portion of said piston comprises an extension of the piston of substantially less diameter than the cylinder engaging body thereof.

3. A hydraulic control device according to claim 1, wherein said slide valve is supported on one end of a valve rod disposed at right angles to said liquid pressure conduit and said liquid discharge passages, and electro-magnetic means operatively associated with the other end of said rod for imparting axial movement thereto with a corresponding movement of said valve.

4. A hydraulic control device according to claim 3, wherein said electro-magnetic means comprises a magnetic core on the other end of said valve rod, and a short stroke double magnet within which said core is disposed. V

5. A hydraulic control device according to claim 1, wherein said passage in communication with said liquid pressure conduit and said pressure medium chamber includes a. cylindrical wallcoaxial with said valve rod, a second cylindrical wall spaced from said first wall and being disposed between said above referred to passage and said second liquid discharge passage, said second cylindrical wall being of the same diameter as said first cylindrical'wall, said valve rod including an elongated cylindrical portion of less diameter than said walls and being reciprocable within said first wall, and said valve comprising a cylindrical portion of the same diameter as said Walls and being alternately engageahle therewith for the purpose set forth.

6. A hydraulic control device according to claim 1, wherein said liquid pressure conduit and said liquid discharge passages extend through said housing transversely thereof and in parallel relation to one another whereby the -housings of a plurality of control units may be disposed in side-by-side relation and have a common liquid admission and a common liquid discharge while said units are capable of independent influence on the working cylinder. t

References Cited in the file of this patent UNITED STATES PATENTS 2,511,405 a Mott Aug. 1; 1950 

